Thermostatic switch



Jan. 9, 1951 J. J. GRACE 2,537,582

THERMosTA'rIc SWITCH Filed June a, 1948 I N VEN TOR. .fait n f [ra'ce transparent material, so that the dial 9 and the pointer 1 may be seen by a person standing in front of the thermostat, and through this front panel is formed an opening I4 through which a metal sleeve or bushing I5 is mounted. A tubular shaft I6 is rotatably mounted through the bushing I5 and has its forward portion I1 externally reduced in diameter and of such length that it projects forwardly from the front panel a sufficient distance tc carry a knob IB which is secured to the tubular shaft by a set screw I9. A second shaft 2li of greater length than the tubular shaft is rotatably mounted through the tubular shaft and projects forwardly from the front end of the outer tubular shaft so that a kno-b 2| may be mounted upon the forward portion of the inner shaft and secured thereon by a set screw 22. A disk or slip ring 23` fits about the rear end portion of the inner shaft between its head 24 and the rear end of the outer shaft I6 and when the knob 2| is applied and its set screw 22 tightened the ring will-be connedwbetween the head of the inner shaft and the rear end of the outer shaft and frictionally gripped thereby.

A wire 25 connects the ring with the negative side of a battery 26, or equivalent source of electric energy, and from the positive side of this battery extends a wire 21 which is attached to one terminal of an electric bell, buzzer, light or equivalent signalling device, 28. The other terminal of the signalling device is connected with the shaft 8 by a wire 29 and when the gap between the wires 25 and 29 is closed the signal will be energized and thus give warning that a temperature variation of predetermined extent has been reached.`

In order to allow closing of-the gap between the wires there have been provided pointers or arrows 39 and 3| formed of conductive material and carried by the rear end of the outer shaft I1 and the head 24 of the innershaft 20. These arrows project radially from the shafts and have mid-portions crimped to form arms 32 and 33 Whichproject rearwardly from the pointers and are of such length that they are in the path of movement of the pointer or arrow 1. The arrows and'3| are Visiblethrough the transparent front panel 2 and by grasping the knobs I8 and 2|` the shafts may-be individually rotated and the .arrows swung'about the dial 9 until they are disposed at'desired markings on the dial. When soadjusted the arrows 30 and 3| will be spaced at opposite sides ofthe arrow 1 and as the arrow Ijmoves in responserto temperature changes it will eventually engage the arm 32 of the arrow 30 or lthe arm 3 3 of the arrow 3|. Whenl this occursf the circuit.4 will be closed and the signal energized. It will be ,seenthat'the arrows 30 and 3`|=serve not only as setting arrowsbut also as adjustable contacts which `are manually shiftable to positions in predetermined spaced relation to opposite sides of the arrow 1 which serves as .a movable contact. As lthe ring 23 is gripped between the heads of the two shafts it is possible to turn the shafts as a unit after the arrows 39 move the arrows relative to the thermostat pointer 1 without changing the distance between the arrows. If so desired, an electrically operated control for a heater, refrigerator, or the like may be installed in the circuit instead of the signal and automatically opened or closed in response to temperature variations.

From the foregoing description of the construction of my improved device, the operation thereof and the method of assembly will be readily understood, and it will be seen that I have provided a comparatively simple, inexpensive and efficient means for carrying out the various objects of the invention.

While I have particularly described the elements best adapted to perform the functions set forth, it is apparent that various changes in form, proportion and in the minor details of construction may be resorted to, without departing from the spirit or sacrificing any of the principles of the invention.

Having thus described the invention, what is claimed is:

In a thermostatic signal, a frame having a transparent front panel, a thermostat in said frame spaced rearwardly from the panel and having a dial visible 'through the panel and a pointer of conductive material pivotally mounted in front of the dial centrally thereof and constituting a movable contact extending radially of the dial, a bushing mounted through said panel and disposed concentric with the pivotal mounting of the pointer, a tubular outer shaft rotatably mounted through said bushing and projecting forwardly therefrom and having a head about its rear end abutting the rear end of the bushing, an inner shaft rotatably mounted through the outer shaft and projecting forwardly therefrom, and having a head at its rearend, knobs fitting about the forwardly projecting portions of said shafts and disposed one in front of the other, set screws carried by said knobs and griping the shafts and securing the knobs to the shafts for independent turning of the shafts by r their knobs, a ring fitting about the inner shaft between one of the shafts and gripped by the heads and constituting means for frictionally turning one shaft withthe other, and pointers of conductive material extending from the heads of rsaid shafts radially of the dial at opposite sides of the movable contact and constituting adjustable contacts, said adjustable contacts having crimped portions forming arms extending towards the dial in position for engagement by the movable contact.

` JOHN J. GRACE.

REFERENCES CITED The following lreferences are of record in the file of this patent:

UNITED STATES PATENTS 

